Cartridge for a firearm

ABSTRACT

A long-range precision firearm cartridge case includes a cylindrical body portion extending from a head end to a frusto-conical shoulder. The frusto-conical shoulder is integrally formed with the body portion and a tapered shoulder portion tapering from the body portion to a neck portion. The neck portion terminates in an open mouth at a projectile receiving end. The neck portion and the tapered portion extend longitudinally a distance such that a bullet positioned in the cartridge case extends through the neck portion and the tapered portion a distance no greater than to a plane through the frusto-conical shoulder so that cartridge case useable capacity is maximized.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application No. 62/104,118, filed 16 Jan. 2015.

FIELD OF THE INVENTION

This invention generally relates to ammunition for firearms and a reamer for forming a firing chamber in the firearm to receive the ammunition.

BACKGROUND OF THE INVENTION

In the firearm and ammunition industry, the cartridge for a firearm is essential in determining the speed and power of the bullet once the firearm is fired. Clearly, bullet speed and power can be affected by changing the size of the cartridge and the amount of propellant, such as gun powder, carried by the cartridge. However, it is equally clear that increases in the size of the cartridge and the amount of powder have an upper limit. Also, as the size of the cartridge and amount of powder increases the size of the firearm in which the cartridge is used must increase resulting in a less versatile instrument.

It would be highly advantageous, therefore, to remedy the foregoing and other deficiencies inherent in the prior art.

Accordingly, it is an object of the present invention to provide a new and improved cartridge for a firearm.

It is another object of the present invention to provide a new and improved cartridge for a firearm that maximizes case useable capacity.

Another object of the invention is to provide a new and improved cartridge for a firearm that maximizes bullet speed, resulting in more down range energy and distance, without substantially increasing the size of the case or cartridge.

Another object of the invention is to provide a new and improved cartridge for a firearm that improves projectile or bullet accuracy for longer ranges.

SUMMARY OF THE INVENTION

Briefly, the desired objects of the instant invention are achieved in accordance with a long-range precision firearm cartridge case designed to maximize cartridge case useable capacity. The case is a hollow cylinder including a head end and a projectile receiving end, the cylinder includes a generally cylindrical body portion extending from the head end to a frusto-conical shoulder. The body portion has a central aperture extending into the head end for receipt of a primer and a cartridge extraction groove formed around the periphery of the body portion adjacent the head end. The frusto-conical shoulder is integrally formed with the body portion and a tapered shoulder portion tapers from the body portion to a generally cylindrical integrally formed neck portion. The neck portion extends longitudinally from the shoulder portion and has a diameter smaller than the diameter of the body portion and terminates in an open mouth at the projectile receiving end. The neck portion and the tapered portion extend longitudinally a distance such that a bullet positioned in the cartridge case extends through the neck portion and the tapered portion a distance no greater than to a plane through the frusto-conical shoulder, whereby cartridge case useable capacity is maximized. The desired objects of the instant invention are further realized in accordance with a long-range precision firearm cartridge including a cartridge case and a projectile. The cartridge case including a hollow cylinder with a head end and a projectile receiving end. The cylinder includes a generally cylindrical body portion extending from the head end to a frusto-conical shoulder, the body portion having a central aperture extending into the head end for receipt of a primer and a cartridge extraction groove formed around the periphery of the body portion adjacent the head end. The frusto-conical shoulder is integrally formed with the body portion and a tapered shoulder portion tapering from the body portion to a generally cylindrical integrally formed neck portion. The neck portion extends longitudinally from the shoulder portion and has a diameter smaller than the diameter of the body portion and terminates in an open mouth at the projectile receiving end. A primer fitted into the central aperture extending into the head end in communication with a flash-hole. Combustible propellant in the body portion. A projectile fitted into the projectile receiving end and the neck portion and the tapered portion extending longitudinally a distance such that the projectile positioned in the cartridge case extends through the neck portion and the tapered portion a distance no greater than to a plane through the frusto-conical shoulder, whereby cartridge case useable capacity is maximized;

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and further and more specific objects and advantages of the instant invention will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment thereof taken in conjunction with the drawings, in which:

FIG. 1 is a plan view of a prior art cartridge for use in an AR-15;

FIG. 2 is a plan view of a cartridge in accordance with the present invention, illustrating dimensions in an unfired and a fired configuration;

FIG. 3 is a chart illustrating the differences between the cartridge of FIG. 1 and the cartridge of FIG. 2;

FIG. 4 is a plan view of a cartridge illustrating the “bullet jump” of a cartridge;

FIG. 5 is a schematic illustration of a bore rider reamer for use in preparation of an AR-15 chamber to use the cartridge of FIG. 2; and

FIG. 6 is a schematic illustration of a finish reamer for use in preparation of an AR-15 chamber to use the cartridge of FIG. 2.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Turning now to the drawings, attention is first directed to FIG. 1 which illustrates a prior art cartridge, generally designated 10, that is specifically designed for use in an AR-15 rifle. Cartridge 10 is known as a 223 Remington cartridge in the civilian field and as a 5.56 NATO cartridge in the military. Cartridge 10 includes a case 12 and a projectile or bullet 14. Bullet 14, in this illustration, is an 80 gr Sierra HP Boattail Matchking.

Referring to FIG. 2, a cartridge 20 in accordance with the present invention is illustrated. Cartridge 20 includes a case 22 and a projectile or bullet 24. Case 22 is generally a hollow cylinder having a restricted neck 26 and preferably formed of brass. Case 22 includes a head end 30 and a mouth end 32. Head end 30 includes a central aperture 34 for receipt of a primer (not shown). A generally cylindrical body portion 36 extends from head end 30 to a frusto-conical shoulder 38. Central aperture 34 is in communication with an interior volume 40 defined primarily by case body portion 36. A cartridge extraction groove 42 is formed around the periphery of body portion 36 proximate head end 30. Shoulder 38 is tapered (tapered portion designated 39) from body portion 36 to generally cylindrical neck portion 26. Neck portion 26 has a diameter smaller than the diameter of body portion 36 and terminates in an open mouth 44 at mouth end 32.

Bullet 24 is carried by neck portion 26, filling neck portion 26, with a portion of bullet 24 extending through tapered portion 39 of body portion 22 approximately to a plane through shoulder 38. In the embodiment illustrated, bullet 24 is a Boattail type approximately 80 grains. It will be understood however that a large variety of different bullets may be used, such as 55 gr to 70 gr. The difference in position between bullet 14 and case 12 of FIG. 1 and bullet 24 and case 22 of FIG. 2, as well as the difference in throats and bullet jump, can be seen in the figures. This difference in bullet position results in more useable capacity in case 22 (see chart and description below).

FIG. 4, specifically illustrates a plan view of a cartridge “bullet jump”. Generally, the definition of “bullet jump” is the unrestricted clearance between the ogive of the bullet where the actual .224 cal. (in the present examples) begins, designated 45, on the shank of the bullet to the bore where the bullet engages the actual rifling, designated 46.

Case 22 has nominal dimensions intended to establish a standard cartridge type. Variations from the nominal dimensions are tolerated by minimal deviations. The dimensions of cartridge 20 are described using both pre-fired and fired dimensions in conjunction with a schematic (FIG. 2), the schematic of a chamber bore rider reamer FIG. 5 and finish reamer FIG. 6, designated 50 and 52, respectively. All dimensions illustrated and described are in inches.

Referring specifically to FIG. 3, a chart is illustrated listing major measurements in both the prior art cartridge (223 REM or 5.56 NATO) and showing the major differences. As can be seen from the chart, the length of the case for the 223 REM or 5.56 NATO cartridge is 0.114 inches longer than the case of the present invention but the capacity of the 223 REM or 5.56 NATO cartridge is 0.82 grains less and the useable case capacity is 7.01 grains less. This difference results in the bullet or projectile being driven at 200 fps (feet per second) faster for any barrel length, thus producing more down range energy and distance. Plus, an added advantage is that it will also work well in a bolt action gun as to fit in with lighter bullets, such as 42 gr, 45 gr, 55 gr, 62 gr, to 77 gr varmint cartridges or it can be built into a lightweight youth rifle. In all cases the length will not exceed 2.260 in in the AR 15 or gas operated system. The present improved cartridge basically gives AR 10 in 7.62 capability in an AR 15 platform of 5.56 mm.

Turning to FIG. 5, a bore rider reamer 50 is illustrated that is specifically designed to ream or form a firearm chamber into a chamber compatible with cartridge 20 and FIG. 6 illustrates a finish reamer 52. To this end, it will be noted that the chamber has dimensions slightly larger than an unfired cartridge 20. When cartridge 20 is fired in the chamber formed with reamers 50 and 52 the fired dimensions set forth above (FIG. 2) are achieved. The unfired to fired dimensions, along with the original form, are specifically calculated to maximize powder combustion and direction of the propellant gasses.

Thus, a new and improved cartridge for a firearm is disclosed that maximizes case useable capacity. By carefully designing the diameters of the cartridge and position of the bullet in the case, the maximum efficiency of the cartridge can be achieved. The new and improved cartridge maximizes bullet speed, resulting in more down range energy and distance, without substantially increasing the size of the case or cartridge. Further, the new and improved cartridge improves projectile or bullet accuracy for longer ranges.

Various changes and modifications to the embodiment herein chosen for purposes of illustration will readily occur to those skilled in the art. To the extent that such modifications and variations do not depart from the spirit of the invention, they are intended to be included within the scope thereof, which is assessed only by a fair interpretation of the following claims.

Having fully described the invention in such clear and concise terms as to enable those skilled in the art to understand and practice the same, the invention claimed is: 

1. A long-range precision firearm cartridge case designed to maximizes cartridge case useable capacity comprising: a hollow cylinder includes a head end and a projectile receiving end, the cylinder including a generally cylindrical body portion extending from the head end to a frusto-conical shoulder, the body portion having a central aperture extending into the head end for receipt of a primer and a cartridge extraction groove formed around the periphery of the body portion adjacent the head end; the frusto-conical shoulder is integrally formed with the body portion and a tapered shoulder portion tapering from the body portion to a generally cylindrical integrally formed neck portion, the neck portion extending longitudinally from the shoulder portion and having a diameter smaller than the diameter of the body portion and terminating in an open mouth at the projectile receiving end; and the neck portion and the tapered portion extend longitudinally a distance such that a bullet positioned in the cartridge case extends through the neck portion and the tapered portion a distance no greater than to a plane through the frusto-conical shoulder, whereby cartridge case useable capacity is maximized.
 2. The long-range precision firearm cartridge case as claimed in claim 1 wherein the neck portion and the tapered portion extend longitudinally a distance such that a bullet positioned in the cartridge case extends through the neck portion and the tapered portion approximately to the plane through the frusto-conical shoulder, whereby cartridge case useable capacity is maximized.
 3. The long-range precision firearm cartridge case as claimed in claim 1 wherein the cartridge case useable capacity is increased by at least 7 gr.
 4. The long-range precision firearm cartridge case as claimed in claim 1 wherein the overall size of the cartridge case is not substantially increased compared to prior art cartridge cases and cartridge case useable capacity is increased.
 5. The long-range precision firearm cartridge case as claimed in claim 1 wherein a difference in position between a bullet and the cartridge case determines the difference in throats and bullet jump.
 6. A long-range precision firearm cartridge as claimed in claim 5 wherein the difference results in the bullet or projectile being driven at 200 fps (feet per second) faster for any barrel length, whereby more down range energy and distance are produced.
 7. A long-range precision firearm cartridge case as claimed in claim 1 including a firearm chamber reamer for use with the cartridge case.
 8. A long-range precision firearm cartridge comprising: a cartridge case including: a hollow cylinder includes a head end and a projectile receiving end, the cylinder including a generally cylindrical body portion extending from the head end to a frusto-conical shoulder, the body portion having a central aperture extending into the head end for receipt of a primer and a cartridge extraction groove formed around the periphery of the body portion adjacent the head end; the frusto-conical shoulder is integrally formed with the body portion and a tapered shoulder portion tapering from the body portion to a generally cylindrical integrally formed neck portion, the neck portion extending longitudinally from the shoulder portion and having a diameter smaller than the diameter of the body portion and terminating in an open mouth at the projectile receiving end; and a primer fitted into the central aperture extending into the head end in communication with a flash-hole; combustible propellant in the body portion; and a projectile fitted into the projectile receiving end, the neck portion and the tapered portion of the cartridge case extending longitudinally a distance such that the projectile positioned in the cartridge case extends through the neck portion and the tapered portion a distance no greater than to a plane through the frusto-conical shoulder, whereby cartridge case useable capacity is maximized.
 9. The long-range precision firearm cartridge case as claimed in claim 8 wherein the neck portion and the tapered portion extend longitudinally a distance such that the projectile positioned in the cartridge case extends through the neck portion and the tapered portion approximately to the plane through the frusto-conical shoulder, whereby cartridge case useable capacity is maximized.
 10. The long-range precision firearm cartridge case as claimed in claim 8 wherein the combustible propellant in the body portion of the cartridge case is increased by at least 7 gr.
 11. The long-range precision firearm cartridge case as claimed in claim 8 wherein the overall size of the cartridge case is not substantially increased compared to prior art cartridge cases and cartridge case useable capacity is increased.
 12. The long-range precision firearm cartridge case as claimed in claim 8 wherein a difference in position between the projectile and the cartridge case over prior art projectiles and cartridge cases determines the difference in throat and bullet jump.
 13. A long-range precision firearm cartridge as claimed in claim 12 wherein the difference results in the bullet or projectile being driven at 200 fps (feet per second) faster for any barrel length, whereby more down range energy and distance are produced.
 14. A long-range precision firearm cartridge as claimed in claim 8 including a firearm chamber reamer for use with the cartridge case. 